The market in stolen historical documents has gotten so hot that federal investigators have launched an operation to retrieve what belongs to the government

On the face of it, the Washington Capital Area Historical Autograph and Manuscript Show seemed like many such shows held around the country each year. Some 20 top dealers gathered at an Alexandria, Va., hotel on Dec. 9 to peddle thousands of autographs, letters and official papers of the famous — many of the more expensive items locked in glass cases. But among the customers wandering through the exhibits this time were two investigators from the National Archives. They passed out brochures on how to spot historical documents stolen from the government and chatted with the dealers to let them know that the feds are now becoming more interested in retrieving the valuable loot. The investigators also quietly browsed through the wares on display, looking for anything that might belong to the Archives.

During this particular visit the document hunters found none, but they expect other forays will turn up important contraband. The investigators are part of Operation Historic Protector, which the Archive's Inspector General's Office launched in November to combat what many fear is a growing threat to the federal government's historical repository, as well as to state archives and university libraries: the pilfering of old letters, documents, maps, photographs, books and other historical artifacts.

The National Archives has beefed up security in recent years, with video cameras and staffers watching outside researchers who review material in its reading rooms. But the Archives and other repositories around the country have suffered a number of heists in recent years.